58] The Classification of Lower Organisms 



Orders Heliolithae and Orthlithinae Deflandre in Grasse Traite Zool. 1, fasc. 

 1: 452, 457 (1952). 

 Brown or colorless Heterokonta, the swimming cells of typical examples with 

 two flagella which are respectively pantoneme and acroneme. In the exceptional 

 family Trimastigida there are a pair of equal flagella and a third flagellum shorter 

 or longer than these; the detailed structure of the flagella of this family is unknown. 

 Cells of pigmented types contain usually one or two lateral band-shaped plastids. 

 Details of nuclear division are known chiefly by the observations of Doflein (1918, 

 1922) on Ochromonas. The flagella spring from a granule which may be identified as 

 a blepharoplast, near which lies the nucleus. The blepharoplast is connected through 

 two stainable strands (rhizoplasts) to two granules, recognizable as centrosomes, on 

 the two sides of the nucleus. The spindle forms within the intact nuclear membrane 

 with its poles at the centrosomes. The chromosome number appears to be about 4. 

 The nuclear membrane presently disappears. At metaphase, the rhizoplasts are found 

 to lead to separate blepharoplasts, each bearing two flagella. Sexual processes are 

 scarcely known in this group. Schiller (1926) observed in Dinobryon the division of 

 calls into two which are released to swim and conjugate in pairs. 



This order is believed to represent the direct ancestry of the two following, and 

 also of the typical brown algae. 

 1. Not filamentous. 



2. Flagellate stages with a pair of equal 

 flagella and a third which is shorter or 



longer Family 1. Trimastigida. 



2. Flagellate stages with two unequal 

 flagella. 



3. Without calcareous structures at- 

 tached to the cell walls. 



4. Cells not enclosed in loricae, 

 i. e., open shells. 



5. Not flagellate in the vege- 

 tative condition Family 2. Chrysocapsacea. 



5. Flagellate in the vegeta- 

 tive condition, not forming 

 free-swimming circular or 



globular colonies Family 3. Monadina. 



5. Free-swimming circular or 



globular colonies Family 4. Syncryptida. 



4. Cells enclosed in loricae Family 5. Dinobryina. 



3. With calcareous structures at- 

 tached to the cell walls Family 6. Hymenomonadacea. 



1. Filamentous Family 7. Phaeothamnionacea. 



Family 1. Trimastigida [Trimastigidae] Kent Man. Inf. 1: 307 (1880). Family 

 Trimastigaceae Senn in Engler and Prantl. Nat. Pflanzcnfam. I Teil, .\bt. la: 141 

 (1900). Family Prymncsiidae Hall Protozoology 127 (1953). Organisms producing 

 swimming cells with a pair of equal flagella and a third flagellum longer or shorter 

 than these. With a vegetative stage as globular non-motile colonies as large as pin- 

 heads, of pigmented cells; marine: Phacocystis. Motile solitary cells, pigmented: 

 Prymncsium, Chrysochromidina; Platychrysis with an amoeboid stage. Motile 

 solitary cells, not pigmented: Dallingeria, Trimastix, Macromastix. 



